Internal combustion engines include a crank shaft which delivers torque. The crank shaft is usually connected to an output shaft, either through a clutch or a transmission. It is necessary to support the engine and shaft, and in the prior art, various suggestions have been made for support structures, including some elastomeric, or rubber-like material placed between the ultimate supporting structure and the engine and the shaft. Such suggestions have generally been provided for automotive applications and, to a lesser extent, for engine testing applications. In such prior art, the principle concern has been with the reduction or elimination of vibrations which originate in the engine, so as to avoid transmission of these vibrations from the engine into the supporting structure, such as the automobile frame, and thence into the passenger compartment. In such environments, the vibrations are comparatively minor in nature, and do not usually prevail for substantial lengths of time. For example, in most automotive applications, the automobile is seldom driven without stopping for longer than eight or ten hours.
In general, the supporting structure between the frame and the engine has included an elastomeric body, usually placed in compression, but in some installations, the elastomeric body has been placed in tension. Such prior art suggestions have not been directed to the problem of isolating the engine from sustained cyclical vibrations imposed over a long period of time onto the engine from the load, and which cyclical vibrations are of substantial magnitude.
Among the known prior art relevant to vibration damping arrangements included in the mounting of engines are the following U.S. Pat. Nos.: Lord 2,028,549; Lord 2,028,551; Scott 2,083,277; Cline 2,565,473.